Well, 6 is something of a small sample size. It would not surprise me at all if the i180 has a good chance at Tv and he just crapped out on his luck. It would similarly not surprise me at all if the chance of a Tv is only around 5-10 percent, and what he got was to be expected, either.

The only thing that would surprise me would be a complete inability to get Tv crafting Materia out of these accessories.